Glass block must be used as a non-load bearing material. All construction above glass block panels must be independently supported. Individual glass block panels must be isolated within their openings with expansion strip material at head and jam locations with no loads imposed on the glass black panel. Glass block panels are mortared at the sill. Sills should be coated with a water based asphalt emulsion prior to laying the first course of glass block.
Installed weights of glass block walls are 20 pounds per square foot of wall area for Premiere Series blocks; 30 pounds per square foot for Thickset Series (thick-faced) block; and 40 pounds per square foot for VISTABRIK® and solid glass block units. All structural members supporting glass block construction must be designed and sized for maximum deflection of L/600.
For exterior applications the building codes allow the use of types N or S mortar utilizing Portland cement, and sand that complies to ASTM(C)-144. The use of accelerators and/or acid washing is not recommended. Nine gauge ladder type reinforcing is to be used in horizontal joints with maximum spacing of 16 inches on center.
Glass block panels are to be framed and anchored at head and jam locations with either a channel type restraint or with PC panel anchors that give the wall a much cleaner look. Panel anchors are spaced at no more then 16 inches on center up both jambs and across the head.
How large of a glass block panel can I design?
Assuming a normal design wind load of 20 PSF (or 78-80 mph wind) and based on using our Premiere series (3 and 7/8 inch thick) glass block products, the maximum exterior size panel should not be larger then 144 square feet with limiting dimensions of either 20 feet in height or 25 feet in length - without exceeding the maximum area of 144 square feet per panel. There is a 2.7 safety factor incorporated within this criteria.
For areas of glass block larger than 144 square feet, the use of structural columns or mullions must be used for long expanses of glass block. For vertically high expanses of glass block must be used to separate and anchor long horizontal expanses of glass block the use of supporting shelf angles must be used to sub-divide these walls.
The maximum area of interior panels should not be greater than 250 square feet with similar limiting dimensions per panel of either 20 feet in height or 25 feet in length.
How tight of a radius can I make with glass block?
Minimum recommended radii dependent on the size of glass block to be used. The tightest radius recommended, measured to the interior face of the wall is 32 inches using the 4 inch by 8 inch glass block units with the 8 inch side oriented vertically. The other minimum radii recommended are 48 ½ inches when using the 6 inch by 6 inch block, 65 inches when using the 8 inch by 8 inch block, and 98 ½ inches when using the 12 inch by 12 inch block. In all cases this will result in a 1/8 inch thick vertical mortar joint on the interior side of the wall and 5/8 inch thick vertical mortar joint on the exterior side of the wall.
For a tighter radius, our newly introduced ARQUE® glass block which is a curved face block with tapered sides will achieve a 12 inch radius to the interior face and a 16 inch radius to the exterior face. By alternating other sizes of glass block in between ARQUE® glass block units, interior radii of 20 to 30 inches can be achieved.
